Assessment of lexical semantic judgment abilities in alcohol-dependent subjects: An fMRI study

Neuropsychological studies have shown that alcohol dependence is associated with neurocognitive deficits in tasks requiring memory, perceptual motor skills, abstraction and problem solving, whereas language skills are relatively spared in alcoholics despite structural abnormalities in the language-related brain regions. To investigate the preserved mechanisms of language processing in alcohol-dependents, functional brain imaging was undertaken in healthy controls (n=18) and alcohol-dependents (n=16) while completing a lexical semantic judgment task in a 3 T MR scanner. Behavioural data indicated that alcohol-dependents took more time than controls for performing the task but there was no significant difference in their response accuracy. fMRI data analysis revealed that while performing the task, the alcoholics showed enhanced activations in left supramarginal gyrus, precuneus bilaterally, left angular gyrus, and left middle temporal gyrus as compared to control subjects. The extensive activations observed in alcoholics as compared to controls suggest that alcoholics recruit additional brain areas to meet the behavioural demands for equivalent task performance. The results are consistent with previous fMRI studies suggesting compensatory mechanisms for the execution of task for showing an equivalent performance or decreased neural efficiency of relevant brain networks. However, on direct comparison of the two groups, the results did not survive correction for multiple comparisons; therefore, the present findings need further exploration.     

Short-term hypoxia/reoxygenation activates the angiogenic pathway in rat caudate putamen

In response to hypoxia, tissues have to implement numerous mechanisms to enhance oxygen delivery, including the activation of angiogenesis. This work investigates the angiogenic response of the hypoxic caudate putamen after several recovery times. Adult Wistar rats were submitted to acute hypoxia and analysed after 0 h, 24 h and 5 days of reoxygenation. Expression of hypoxia-inducible factor-1 alfa (HIF-1α) and angiogenesis-related genes including vascular endothelial growth factor (VEGF), adrenomedullin (ADM) and transforming growth factor-beta 1 (TGF-β1) was determined by both RT-PCR and ELISA. For vessel labelling, lectin location and expression were analysed using histochemical and image processing techniques (fractal dimension). Expression of Hif-1α, Vegf, Adm and Tgf-β1 mRNA rose immediately after hypoxia and this increase persisted in some cases after 5 days post-hypoxia. While VEGF and TGF-β1 protein levels increased parallel to mRNA expression, ADM remained unaltered. The quantification of the striatal vessel network showed a significant augmentation at 24 h of reoxygenation. These results reveal that not only short-term hypoxia, but also the subsequent reoxygenation period, up-regulate the angiogenic pathway in the rat caudate putamen as a neuroprotective mechanism to hypoxia that seeks to maintain a proper blood supply to the hypoxic tissue, thereby minimizing the adverse effects of oxygen deprivation.     

Loss of meiosis in Aspergillus

If strictly mitotic asexual fungi lack recombination, the conventional view predicts that they are recent derivatives from older meiotic lineages. We tested this by inferring phylogenetic relationships among closely related meiotic and strictly mitotic taxa with Aspergillus conidial (mitotic) states. Phylogenies were constructed by using DNA sequences from the mitochondrial small ribosomal subunit, the nuclear ribosomal internal transcribed spacers, and the nuclear 5.8S ribosomal gene. Over 920 bp of sequence was analyzed for each taxon. Phylogenetic analysis of both the mitochondrial and nuclear data sets showed at least four clades that possess both meiotic and strictly mitotic taxa. These results support the hypothesis that strictly mitotic lineages arise frequently from more ancient meiotic lineages with Aspergillus conidial states. Many of the strictly mitotic species examined retained characters that may be vestiges of a meiotic state, including the production of sclerotia, sclerotium-like structures, and hulle cells.      

Structural basis for the interaction of SARS‐CoV‐2 virulence factor nsp1 with DNA polymerase α–primase

The molecular mechanisms that drive the infection by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2)—the causative agent of coronavirus disease 2019 (COVID‐19)—are under intense current scrutiny to understand how the virus operates and to uncover ways in which the disease can be prevented or alleviated. Recent proteomic screens of the interactions between viral and host proteins have identified the human proteins targeted by SARS‐CoV‐2. The DNA polymerase α (Pol α)–primase complex or primosome—responsible for initiating DNA synthesis during genomic duplication—was identified as a target of nonstructural protein 1 (nsp1), a major virulence factor in the SARS‐CoV‐2 infection. Here, we validate the published reports of the interaction of nsp1 with the primosome by demonstrating direct binding with purified recombinant components and providing a biochemical characterization of their interaction. Furthermore, we provide a structural basis for the interaction by elucidating the cryo‐electron microscopy structure of nsp1 bound to the primosome. Our findings provide biochemical evidence for the reported targeting of Pol α by the virulence factor nsp1 and suggest that SARS‐CoV‐2 interferes with Pol α''s putative role in the immune response during the viral infection.     

Patch-clamp recording of charge movement, Ca(2+) current, and Ca(2+) transients in adult skeletal muscle fibers

Intramembrane charge movement (Q), Ca(2+) conductance (G(m)) through the dihydropyridine-sensitive L-type Ca(2+) channel (DHPR) and intracellular Ca(2+) fluorescence (F) have been recorded simultaneously in flexor digitorum brevis muscle fibers of adult mice, using the whole-cell configuration of the patch-clamp technique. The voltage distribution of Q was fitted to a Boltzmann equation; the Q(max), V(1/2Q), and effective valence (z(Q)) values were 41 +/- 3.1 nC/&mgr;F, -17.6 +/- 0.7 mV, and 2.0 +/- 0.12, respectively. V(1/2G) and z(G) values were -0.3 +/- 0.06 mV and 5.6 +/- 0.34, respectively. Peak Ca(2+) transients did not change significantly after 30 min of recording. F was fit to a Boltzmann equation, and the values for V(F1/2) and z(F) were 6.2 +/- 0.04 mV and 2.4, respectively. F was adequately fit to the fourth power of Q. These results demonstrate that the patch-clamp technique is appropriate for recording Q, G(m), and intracellular [Ca(2+)] simultaneously in mature skeletal muscle fibers and that the voltage distribution of the changes in intracellular Ca(2+) can be predicted by a Hodgkin-Huxley model.     

土壤低剂量芘污染对蚯蚓若干生化指标的影响

通过人工污染土壤的方法,设计芘的暴露浓度为0、60、120、240、480、960μg.kg-1.暴露实验进行1、3、7和14d后,分别检测蚯蚓内脏中细胞色素P450含量、谷胱甘肽转移酶(GST)、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量.结果表明,在供试浓度范围内,蚯蚓内脏中各生化指标对污染物暴露指示的敏感性存在差异:其中P450含量、GST和SOD活性最为敏感;POD和CAT活性次之;而MDA含量未对低剂量的芘暴露起到明显的指示作用.研究同时发现,低剂量污染物暴露的时间效应要强于剂量效应的影响.因而,在进行生态毒性诊断时,采用多指标和多时段的检测对增强指示的灵敏性和有效性尤为重要.     

Multiple actins in drosophila melanogaster

The tissue and developmental specificities of the three Drosophila isoactins, originally identified in primary myogenic cultures and in the permanent Schneider L-2 cell line, have been investigated. Of these three isoactins (I, II, and III), actins I and II are stable and actin III is unstable. Two-dimensional polyacrylamide gel electrophoretic analyses of total cellular extracts after 1-h [(35)S]methionine pulses were performed on a large variety of embryonic, larval, and adult muscle and nonmuscle tissues. The results suggest that isoactins II and III are generalized cellular actins found in all drosophila cell types. Actin I, on the other hand, is muscle-associated and is found exclusively in supercontractile muscle (such as larval body wall and larval and adult viscera) including primary myogenic cell cultures. Although actin I synthesis is not detectable during very early embryogenesis, it is detectable by 25 h and actin I is a major stable actin in all larval muscle tissues. Actin I is synthesized in reduced amounts relative to the other actins in late third instar larvae but is again a major product of actin synthesis in the adult abdomen. A stable actin species with the same pI as actin III has been identified in the adult thorax and appears to be unique to flight muscle tissue. This new stable form of thoracic actin may be the result of a stabilization of the actin III found in other tissues or may be an entirely separate gene product.     

Cytochemical demonstration of hydrogen peroxide in polymorphonuclear leukocyte phagosomes

Phagocytosis by polymorphonuclear leukocytes (PMN) is accompanied by specific morphological and metabolic events which may result in the killing of internalized micro-organism. Hydrogen peroxide is produced in increased amounts during phagocytosis (17) and in combination with myeloperoxidase and halide ions constitute a potent, microbicidal mechanism (8,9,11). There can be direct iodination of micro-organisms (10), or alternatively, other intermediate reaction products, i.e. chloramines and aldehydes (21), can exert a microbicidal effect. The H2O2-peroxidase-halide system is presumed to operate within the phagocytic vacuole (12,18). Myeloperoxidase, present in the primary granules of PMN, enters the phagocytic vacuole during degranulation (1,4,7), and halide ions are probably derived from the extracellular medium or are present in the PMN (see 11, 18). For the operation of this system in intact cells, the presence of H2O2 in the phagocytic vacuole is necessary, and indeed this has been suggested by the work of several investigators (12, 18, 21). In the present investigation, the diaminobenzidine reaction of Graham and Karnovsky (5), modified to utilize endogenous myeloperoxidase and hydrogen peroxide, has been applied to actively phagocytizing PMN to demonstrate cytochemically the presence of H2O2 in the phagocytic vacuole.